Steerable segmented endoscope and method of insertion

ABSTRACT

A steerable endoscope has an elongated body with a selectively steerable distal portion and an automatically controlled proximal portion. The endoscope body is inserted into a patient and the selectively steerable distal portion is used to select a desired path within the patient&#39;s body. When the endoscope body is advanced, an electronic motion controller operates the automatically controlled proximal portion to assume the selected curve of the selectively steerable distal portion. Another desired path is selected with the selectively steerable distal portion and the endoscope body is advanced again. As the endoscope body is further advanced, the selected curves propagate proximally along the endoscope body, and when the endoscope body is withdrawn proximally, the selected curves propagate distally along the endoscope body. This creates a serpentine motion in the endoscope body allowing it to negotiate tortuous curves along a desired path through or around and between organs within the body.

CROSS-REFERENCE TO OTHER APPLICATIONS

[0001] The present application is a continuation of U.S. patentapplication Ser. No. 09/969,927 entitled “Steerable Segmented Endoscopeand Method of Insertion” filed Oct. 2, 2001, which is acontinuation-in-part of U.S. patent application Ser. No. 09/790,204entitled “Steerable Endoscope and Improved Method of Insertion” filedFeb. 20, 2001, which claims priority of U.S. Provisional PatentApplication No. 60/194,140 filed Apr. 3, 2000, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to endoscopes andendoscopic medical procedures. More particularly, it relates to a methodand apparatus to facilitate insertion of a flexible endoscope along atortuous path, such as for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

[0003] An endoscope is a medical instrument for visualizing the interiorof a patient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

[0004] Colonoscopy is a medical procedure in which a flexible endoscope,or colonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-19 mm in diameter,and includes a fiberoptic imaging bundle or a miniature camera locatedat the instrument's tip, illumination fibers, one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels. The colonoscope is inserted via thepatient's anus and is advanced through the colon, allowing direct visualexamination of the colon, the ileocecal valve and portions of theterminal ileum. Insertion of the colonoscope is complicated by the factthat the colon represents a tortuous and convoluted path. Considerablemanipulation of the colonoscope is often necessary to advance thecolonoscope through the colon, making the procedure more difficult andtime consuming and adding to the potential for complications, such asintestinal perforation. Steerable colonoscopes have been devised tofacilitate selection of the correct path though the curves of the colon.However, as the colonoscope is inserted farther and farther into thecolon, it becomes more difficult to advance the colonoscope along theselected path. At each turn, the wall of the colon must maintain thecurve in the colonoscope. The colonoscope rubs against the mucosalsurface of the colon along the outside of each turn. Friction and slackin the colonoscope build up at each turn, making it more and moredifficult to advance and withdraw the colonoscope. In addition, theforce against the wall of the colon increases with the buildup offriction. In cases of extreme tortuosity, it may become impossible toadvance the colonoscope all of the way through the colon.

[0005] Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. Pat. Nos., the disclosures of which are herebyincorporated by reference in their entirety: 4,753,223; 5,337,732;5,662,587; 4,543,090; 5,383,852; 5,487,757 and 5,337,733.

SUMMARY OF THE INVENTION

[0006] In keeping with the foregoing discussion, the present inventiontakes the form of a steerable endoscope for negotiating tortuous pathsthrough a patient's body. The steerable endoscope can be used for avariety of different diagnostic and interventional procedures, includingcolonoscopy, upper endoscopy, bronchoscopy, thoracoscopy, laparoscopyand video endoscopy. The steerable endoscope is particularly well suitedfor negotiating the tortuous curves encountered when performing acolonoscopy procedure.

[0007] The steerable endoscope has an elongated body with a manually orselectively steerable distal portion and an automatically controlledproximal portion. The selectively steerable distal portion can beselectively steered or bent up to a full 180 degree bend in anydirection. A fiberoptic imaging bundle and one or more illuminationfibers extend through the body from the proximal end to the distal end.Alternatively, the endoscope can be configured as a video endoscope witha miniaturized video camera, such as a CCD camera, which transmitsimages to a video monitor by a transmission cable or by wirelesstransmission, or alternatively through the use of CMOS imagingtechnology. Optionally, the endoscope may include one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels.

[0008] A proximal handle attached to the elongate body includes anocular for direct viewing and/or for connection to a video camera, aconnection to an illumination source and one or more luer lock fittingsthat are connected to the instrument channels. The handle is connectedto a steering control for selectively steering or bending theselectively steerable distal portion in the desired direction and to anelectronic motion controller for controlling the automaticallycontrolled proximal portion of the endoscope. An axial motion transduceris provided to measure the axial motion of the endoscope body as it isadvanced and withdrawn. Optionally, the endoscope may include a motor orlinear actuator for both automatically advancing and withdrawing theendoscope, or for automatically advancing and passively withdrawing theendoscope.

[0009] One preferable embodiment of the endoscope includes a segmentedendoscopic embodiment having multiple independently controllablesegments which may be individually motorized and interconnected byjoints. Each of the individual adjacent segments may be pivotable abouttwo independent axes to offer a range of motion during endoscopeinsertion into a patient.

[0010] This particular embodiment, as mentioned, may have individualmotors, e.g., small brushed DC motors, to actuate each individualsegment. Furthermore, each segment preferably has a backbone segmentwhich defines a lumen therethrough to allow a continuous lumen to passthrough the entire endoscopic instrument to provide an access channelthrough which wires, optical fibers, air and/or water channels, variousendoscopic tools, or any variety of devices and wires may be routed. Theentire assembly, i.e., motors, backbone, cables, etc., may be encased orcovered in a biocompatible material, e.g., a polymer, which is alsopreferably lubricious to allow for minimal frictional resistance duringendoscope insertion and advancement into a patient. This biocompatiblecover may be removable from the endoscopic body to expose the motors andbackbone assembly to allow for direct access to the components. This mayalso allow for the cover to be easily replaced and disposed after use ina patient.

[0011] The method of the present invention involves inserting the distalend of the endoscope body into a patient, either through a naturalorifice or through an incision, and steering the selectively steerabledistal portion to select a desired path. When the endoscope body isadvanced or inserted further into the patient's body, the electronicmotion controller operates the automatically controlled proximal portionof the body to assume the selected curve of the selectively steerabledistal portion. This process is repeated by selecting another desiredpath with the selectively steerable distal portion and advancing theendoscope body again. As the endoscope body is further advanced, theselected curves propagate proximally along the endoscope body.Similarly, when the endoscope body is withdrawn proximally, the selectedcurves propagate distally along the endoscope body, either automaticallyor passively. This creates a sort of serpentine motion in the endoscopebody that allows it to negotiate tortuous curves along a desired paththrough or around and between organs within the body.

[0012] The method can be used for performing colonoscopy or otherendoscopic procedures, such as bronchoscopy, thoracoscopy, laparoscopyand video endoscopy. In addition, the apparatus and methods of thepresent invention can be used for inserting other types of instruments,such as surgical instruments, catheters or introducers, along a desiredpath within the body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 shows a prior art colonoscope being employed for acolonoscopic examination of a patient's colon.

[0014]FIG. 2 shows a first embodiment of the steerable endoscope of thepresent invention.

[0015]FIG. 3 shows a second embodiment of the steerable endoscope of thepresent invention.

[0016]FIG. 4 shows a third embodiment of the steerable endoscope of thepresent invention.

[0017]FIG. 5 shows a fourth embodiment of the steerable endoscope of thepresent invention.

[0018]FIG. 6 shows a wire frame model of a section of the body of theendoscope in a neutral or straight position.

[0019]FIG. 7 shows the wire frame model of the endoscope body shown inFIG. 6 passing through a curve in a patient's colon.

[0020]FIG. 8 shows a representative portion of an alternative endoscopicbody embodiment having multiple segments interconnected by joints.

[0021]FIG. 9 shows a partial schematic representation of the embodimentof FIG. 8 showing two segments being pivotable about two independentaxes.

[0022]FIG. 10 shows a preferable endoscope embodiment having motorizedsegmented joints.

[0023] FIGS. 11A-11B show exploded isometric assembly views of twoadjacent segments and an individual segment, respectively, from theembodiment shown in FIG. 10.

[0024] FIGS. 12-17 show the endoscope of the present invention beingemployed for a colonoscopic examination of a patient's colon.

[0025] FIGS. 18-20 show an endoscope being advanced through a patient'scolon while a datum measures the distance advanced into the patient.

[0026]FIG. 21 shows a schematic representation of one embodiment of acontrol system which may be used to control and command the individualsegments of a segmented endoscopic device of the type shown in FIGS.8-11B.

[0027]FIG. 22 shows a flow chart embodiment for the master controlleralgorithm which may be used to control the overall function duringendoscope insertion into a patient.

[0028]FIG. 23 shows a flowchart embodiment of the segment controlleralgorithm.

[0029] FIGS. 24-26 shows a non-contact method of measurement andtracking of an endoscope using an external navigational system such as aglobal positioning system.

DETAILED DESCRIPTION OF THE INVENTION

[0030]FIG. 1 shows a prior art colonoscope 500 being employed for acolonoscopic examination of a patient's colon C. The colonoscope 500 hasa proximal handle 506 and an elongate body 502 with a steerable distalportion 504. The body 502 of the colonoscope 500 has been lubricated andinserted into the colon C via the patient's anus A. Utilizing thesteerable distal portion 504 for guidance, the body 502 of thecolonoscope 500 has been maneuvered through several turns in thepatient's colon C to the ascending colon G. Typically, this involves aconsiderable amount of manipulation by pushing, pulling and rotating thecolonoscope 500 from the proximal end to advance it through the turns ofthe colon C. After the steerable distal portion 504 has passed, the wallof the colon C maintains the curve in the flexible body 502 of thecolonoscope 500 as it is advanced. Friction-develops along the body 502of the colonoscope 500 as it is inserted, particularly at each turn inthe colon C. Because of the friction, when the user attempts to advancethe colonoscope 500, the body 502′ tends to move outward at each curve,pushing against the wall of the colon C, which exacerbates the problemby increasing the friction and making it more difficult to advance thecolonoscope 500. On the other hand, when the colonoscope 500 iswithdrawn, the body 502″ tends to move inward at each curve taking upthe slack that developed when the colonoscope 500 was advanced. When thepatient's colon C is extremely tortuous, the distal end of the body 502becomes unresponsive to the user's manipulations, and eventually it maybecome impossible to advance the colonoscope 500 any farther. Inaddition to the difficulty that it presents to the user, tortuosity ofthe patient's colon also increases the risk of complications, such asintestinal perforation.

[0031]FIG. 2 shows a first embodiment of the steerable endoscope 100 ofthe present invention. The endoscope 100 has an elongate body 102 with amanually or selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The selectively steerabledistal portion 104 can be selectively steered or bent up to a full 180degree bend in any direction. A fiberoptic imaging bundle 112 and one ormore illumination fibers 114 extend through the body 102 from theproximal end 110 to the distal end 108. Alternatively, the endoscope 100can be configured as a video endoscope with a miniaturized video camera,such as a CCD camera, positioned at the distal end 108 of the endoscopebody 102. The images from the video camera can be transmitted to a videomonitor by a transmission cable or by wireless transmission where imagesmay be viewed in real-time or recorded by a recording device onto analogrecording medium, e.g., magnetic tape, or digital recording medium,e.g., compact disc, digital tape, etc. Optionally, the body 102 of theendoscope 100 may include one or two instrument channels 116, 118 thatmay also be used for insufflation or irrigation, air and water channels,and vacuum channels. The body 102 of the endoscope 100 is highlyflexible so that it is able to bend around small diameter curves withoutbuckling or kinking while maintaining the various channels intact. Whenconfigured for use as a colonoscope, the body 102 of the endoscope 100is typically from 135 to 185 cm in length and approximately 12-13 mm indiameter. The endoscope 100 can be made in a variety of other sizes andconfigurations for other medical and industrial applications.

[0032] A proximal handle 120 is attached to the proximal end 110 of theelongate body 102. The handle 120 includes an ocular 124 connected tothe fiberoptic imaging bundle 112 for direct viewing and/or forconnection to a video camera 126 or a recording device 127. The handle120 is connected to an illumination source 128 by an illumination cable134 that is connected to or continuous with the illumination fibers 114.A first luer lock fitting, 130 and a second luer lock fitting 132 on thehandle 120 are connected to the instrument channels 116, 118.

[0033] The handle 120 is connected to an electronic motion controller140 by way of a controller cable 136. A steering control 122 isconnected to the electronic motion controller 140 by way of a secondcable 13 M. The steering control 122 allows the user to selectivelysteer or bend the selectively steerable distal portion 104 of the body102 in the desired direction. The steering control 122 may be a joystickcontroller as shown, or other known steering control mechanism. Theelectronic motion controller 140 controls the motion of theautomatically controlled proximal portion 106 of the body 102. Theelectronic motion controller 140 may be implemented using a motioncontrol program running on a microcomputer or using anapplication-specific motion controller. Alternatively, the electronicmotion controller 140 may be implemented using, a neural networkcontroller.

[0034] An axial motion transducer 150 is provided to measure the axialmotion of the endoscope body 102 as it is advanced and withdrawn. Theaxial motion transducer 150 can be made in many possible configurations.By way of example, the axial motion transducer 150 in FIG. 2 isconfigured as a ring 152 that surrounds the body 102 of the endoscope100. The axial motion transducer 150 is attached to a fixed point ofreference, such as the surgical table or the insertion point for theendoscope 100 on the patient's body. As the body 102 of the endoscope100 slides through the axial motion transducer 150, it produces a signalindicative of the axial position of the endoscope body 102 with respectto the fixed point of reference and sends a signal to the electronicmotion controller 140 by telemetry or by a cable (not shown). The axialmotion transducer 150 may use optical, electronic or mechanical means tomeasure the axial position of the endoscope body 102. Other possibleconfigurations for the axial motion transducer 150 are described below.

[0035]FIG. 3 shows a second embodiment of the endoscope 100 of thepresent invention. As in the embodiment of FIG. 2, the endoscope 100 hasan elongate body 102 with a selectively steerable distal portion 104 andan automatically controlled proximal portion 106. The steering control122 is integrated into proximal handle 120 in the form or one or twodials for selectively steering, the selectively steerable distal portion104 of the endoscope 100. Optionally, the electronic motion controller140 may be miniaturized and integrated into proximal handle 120, aswell. In this embodiment, the axial motion transducer 150 is configuredwith a base 154 that is attachable to a fixed point of reference, suchas the surgical table. A first roller 156 and a second roller 158contact the exterior of the endoscope body 102. A multi-turnpotentiometer 160 or other motion transducer is connected to the firstroller 156 to measure the axial motion of the endoscope body 102 and toproduce a signal indicative of the axial position.

[0036] The endoscope 100 may be manually advanced or withdrawn by theuser by grasping the body 102 distal to the axial motion transducer 150.Alternatively, the first roller 156 and/or second roller 158 may beconnected to at least one motor, e.g., motor 162, for automaticallyadvancing and withdrawing the body 102 of the endoscope 100.

[0037]FIG. 4 shows a third embodiment of the endoscope 100 of thepresent invention, which utilizes an elongated housing 170 to organizeand contain the endoscope 100. The housing 170 has a base 172 with alinear track 174 to guide the body 102 of the endoscope 100. The housing170 may have an axial motion transducer 150′ that is configured as alinear motion transducer integrated into the linear track 174.Alternatively, the housing 170 may have an axial motion transducer 150″configured similarly to the axial motion transducer 150 in FIG. 2 or 3.The endoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 170. Alternatively, thehousing 170 may include a motor 176 or other linear motion actuator forautomatically advancing and withdrawing the body 102 of the endoscope100. In another alternative configuration, a motor with friction wheels,similar to that described above in connection with FIG. 3, may beintegrated into the axial motion transducer 150″.

[0038]FIG. 5 shows a fourth embodiment of the endoscope 100 of thepresent invention, which utilizes a rotary housing 180 to organize andcontain the endoscope 100. The housing 180 has a base 182 with arotating drum 184 to guide the body 102 of the endoscope 100. Thehousing 180 may have an axial motion transducer 150′″ that is configuredas a potentiometer connected to the pivot axis 186 of the rotating drum184. Alternatively, the housing 180 may have an axial motion transducer150″ configured similarly to the axial motion transducer 150 in FIG. 2or 3. The endoscope 100 may be manually advanced or withdrawn by theuser by grasping the body 102 distal to the housing 180. Alternatively,the housing 180 may include a motor 188 connected to the rotating drum184 for automatically advancing and withdrawing the body 102 of theendoscope 100. In another alternative configuration, a motor withfriction wheels, similar to that described above in connection with FIG.3, may be integrated into the axial motion transducer 150″.

[0039]FIG. 6 shows a wire frame model of a section of the body 102 ofthe endoscope 100 in a neutral or straight position. Most of theinternal structure of the endoscope body 102 has been eliminated in thisdrawing for the sake of clarity. The endoscope body 102 is divided upinto sections 1, 2, 3 . . . 10, etc. The geometry of each section isdefined by four length measurements along the a, b, c and d axes. Forexample, the geometry of section 1 is defined by the four lengthmeasurements l_(1a), l_(1b), l_(1c), l_(1d), and the geometry of section2 is defined by the four length measurements l_(2a), l_(2b), l_(2c),l_(2d), etc. Preferably, each of the length measurements is individuallycontrolled by a linear actuator (not shown). The linear actuators mayutilize one of several different operating principles. For example, eachof the linear actuators may be a self-heating NiTi alloy linear actuatoror an electrorheological plastic actuator, or other known mechanical,pneumatic, hydraulic or electromechanical actuator. The geometry of eachsection may be altered using the linear actuators to change the fourlength measurements along the a, b, c and d axes. Preferably, the lengthmeasurements are changed in complementary pairs to selectively bend theendoscope body 102 in a desired direction. For example, to bend theendoscope body 102 in the direction of the a axis, the measurementsl_(1a), l_(2a), l_(3a) . . . l_(10a) would be shortened and themeasurements l_(1b), l_(2b), l_(3b) . . . l_(10b) would be lengthened anequal amount. The amount by which these measurements are changeddetermines the radius of the resultant curve.

[0040] In the selectively steerable distal portion 104 of the endoscopebody 102, the linear actuators that control the a, b, c and d axismeasurements of each section are selectively controlled by the userthrough the steering control 122. Thus, by appropriate control of the a,b, c and d axis measurements, the selectively steerable distal portion104 of the endoscope body 102 can be selectively steered or bent up to afull 180 degrees in any direction.

[0041] In the automatically controlled proximal portion 106, however,the a, b, c and d direction measurements of each section areautomatically controlled by the electronic motion controller 140, whichuses a curve propagation method to control the shape of the endoscopebody 102. To explain how the curve propagation method operates, FIG. 7shows the wire frame model of a part of the automatically controlledproximal portion 106 of the endoscope body 102 shown in FIG. 6 passing,through a curve in a patient's colon C. For simplicity, an example of atwo-dimensional curve is shown and only the a and b axes will beconsidered. In a three-dimensional curve all four of the a, b, c and daxes would be brought into play.

[0042] In FIG. 7, the endoscope body 102 has been maneuvered through thecurve in the colon C with the benefit of the selectively steerabledistal portion 104 (this part of the procedure is explained in moredetail below) and now the automatically controlled proximal portion 106resides in the curve. Sections 1 and 2 are in a relatively straight partof the colon C, therefore l_(1a)=l_(1b) and l_(2a)=l_(2b). However,because sections 3-7 are in the S-shaped curved section, l_(3a)<l_(3b),l_(4a)<l_(4b) and l_(5a)<l_(5b), but l_(6a)>l_(6b), l_(7a)>l_(7b) andl_(8a)>l_(8b). When the endoscope body 102 is advanced distally by oneunit, section 1 moves into the position marked 1′, section 2 moves intothe position previously occupied by section 1, section 3 moves into theposition previously occupied by section 2, etc. The axial motiontransducer 150 produces a signal indicative of the axial position of theendoscope body 102 with respect to a fixed point of reference and sendsthe signal to the electronic motion controller 140, under control of theelectronic motion controller 140, each time the endoscope body 102advances one unit, each section in the automatically controlled proximalportion 106 is signaled to assume the shape of the section thatpreviously occupied the space that it is now in. Therefore, when theendoscope body 102 is advanced to the position marked 1′, l_(1a)=l_(1b),l_(2a)=l_(2b), l_(3a)=l_(3b), l_(4a)<l_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)>l_(7b) and l_(8a)>l_(8b), and l_(9a)>l_(9b), whenthe endoscope body 102 is advanced to the position marked 1″,l_(1a)=l_(1b), l_(2a)=l₂, l_(3a)=l_(3b), l_(4a)=_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)<l_(7b), l_(8a)>l_(8b), l_(9a)>l_(9b), andl_(10a)>l_(10b). Thus, the S-shaped curve propagates proximally alongthe length of the automatically controlled proximal portion 106 of theendoscope body 102. The S-shaped curve appears to be fixed in space, asthe endoscope body 102 advances distally.

[0043] Similarly, when the endoscope body 102 is withdrawn proximally,each time the endoscope body 102 is moved proximally by one unit, eachsection in the automatically controlled proximal portion 106 is signaledto assume the shape of the section that previously occupied the spacethat it is now in. The S-shaped curve propagates distally along thelength of the automatically controlled proximal portion 106 of theendoscope body 102, and the S-shaped curve appears to be fixed in space,as the endoscope body 102 withdraws proximally.

[0044] Whenever the endoscope body 102 is advanced or withdrawn, theaxial motion transducer 150 detects the change in position and theelectronic motion controller 140 propagates the selected curvesproximally or distally along the automatically controlled proximalportion 106 of the endoscope body 102 to maintain the curves in aspatially fixed position. This allows the endoscope body 102 to movethrough tortuous curves without putting unnecessary force on the wall ofthe colon C.

[0045]FIG. 8 shows a representative portion of an alternative endoscopicbody embodiment 190 which has multiple segments 192 interconnected byjoints 194. In this embodiment, adjacent segments 192 can be moved orangled relative to one another by a joint 194 having at least onedegree-of-freedom, and preferably having multiple degrees-of-freedom,preferably about two axes as shown here. As seen further in FIG. 9, apartial schematic representation 196 of the embodiment 190 is shownwhere two segments 192 may be rotated about joint 194 about the twoindependent axes. The range of motion may be described in relation tospherical axes 198 by angles α and β.

[0046] As mentioned above, such a segmented body may be actuated by avariety of methods. A preferable method involves the use ofelectromechanical motors individually mounted on each individual segmentto move the segments relative to one another. FIG. 10 shows a preferableembodiment 200 having motorized segmented joints. Each segment 192 ispreferably comprised of a backbone segment 202, which also preferablydefines at least one lumen running through it to provide an accesschannel through which wires, optical fibers, air and/or water channels,various endoscopic tools, or any variety of devices and wires may berouted through. The backbone segment may be made of a variety ofmaterials which are preferably biocompatible and which providesufficient strength to support the various tools and other components,e.g., stainless steel. Although much of the description is to anindividual segment 192, each of the segments 192 are preferablyidentical, except for the segment (or first few segments) located at thedistal tip, and the following description readily applies to at least amajority of the segments 192.

[0047] A single motor, or multiple motors depending upon the desiredresult and application, may be attached to at least a majority of thesegments. An embodiment having a single motor on a segment isillustrated in FIG. 10 where an individual motor 204 is preferablyattached to backbone 202 and is sufficiently small and compact enough soas to present a relatively small diameter which is comfortable and smallenough for insertion into a patient without trauma. Motor 204, which isshown here as being a small brushed DC motor, may be used for actuatingadjacent segments 192 and may be controlled independently from othermotors. Various motors, aside from small brushed DC motors, may also beused such as AC motors, linear motors, etc. Each motor 204 alsopreferably contains within the housing not only the electromechanicalmotor assembly EM itself, but also a gear reduction stage GR, and aposition encoder PE. A gear reduction stage GR attached to the motorassembly EM will allow for the use of the motor 204 in its optimal speedand torque range by changing high-speed, low-torque operating conditionsinto a more useful low-speed, high-torque output. The position encoderPE may be a conventional encoder to allow the controlling computer toread the position of the segment's joint 194 by keeping track of theangular rotational movement of the output shaft of the motor 204.

[0048] Each motor 204 has a rotatable shaft which extends from an end ofthe motor 204 to provide for the transmission of power to actuate thesegments 192. Upon this shaft, a spool 206 may be rotatingly attachedwith a first end of the cable 208 further wound about the spool 206. Thecable 208 may then be routed from spool 206 through a channel 212 whichis defined in the cable guide 210 and out through opening 214 (as seenin greater detail in FIGS. 11A-11B) to cable anchor 216, to which thesecond end of the cable 208 is preferably attached, e.g., by crimpingand/or soldering. The cable guide 210 serves to capture the cable 208that is wound about the spool 206. The cable anchor 216 is attachedacross a universal joint pivot 220 to an adjacent segment 192 via a pin218 and may be shaped like a conventional electronic ring connectorhaving a round section defining a hole therethrough for mounting to thesegment 192 and an extension protruding from the anchor 216 forattaching the second end of the cable 208. Cable 208 may comprise a widevariety of filaments, strands, wires, chains, braids, etc. any of whichmay be made of a wide variety of biocompatible materials, e.g., metalssuch as stainless steel, polymers such as plastics and Nylon, etc.

[0049] In operation, when the motor 204 is operated to spin the shaft ina first direction, e.g., clockwise, the spool 206 rotates accordinglyand the cable 208 pulls in a corresponding direction on the adjacentsegment 192 and transmits the torque to subsequently actuate it along afirst axis. When the motor 204 is operated to spin the shaft in a seconddirection opposite to the first, e.g., counter-clockwise, the spool 206again rotates accordingly and the cable 208 would then pull in thecorresponding opposing direction on the adjacent segment 192 tosubsequently transmit the torque and actuate it in the oppositedirection.

[0050]FIGS. 11A and 11B show exploded isometric assembly views of twoadjacent segments and an individual segment, respectively, from theembodiment shown in FIG. 10. As seen in FIG. 11A, backbone 202 is seenwith the lumen 221, which may be used to provide a working channel, asdescribed above. Also seen are channel 212 defined in cable guide 210 aswell as opening 214 for the cable 208 to run through. In interconnectingadjacent segments and to provide the requisite degree-of-freedom betweensegments, a preferable method of joining involves using the universaljoint pivot 220. However, other embodiments, rather than using auniversal joint pivot 220, may use a variety of joining methods, e.g., aflexible tube used to join two segments at their respective centers, aseries of single degree-of-freedom joints that may be closely spaced,etc. This particular embodiment describes the use of the universal jointpivot 220. At the ends of backbone 202 adjacent to other segments, apair of universal yoke members 224 may be formed with a pair ofcorresponding pin openings 226. As the universal joint pivot 220 isconnected to a first pair of yoke members 224 on one segment, acorresponding pair of yoke members 224 from the adjacent segment mayalso be attached to the joint pivot 220.

[0051] As seen further in FIG. 11B, the universal joint pivot 220 isshown in this embodiment as a cylindrical ring having two sets ofopposing receiving holes 228 for pivotally receiving corresponding yokemembers 224. The receiving holes 228 are shown as being spaced apart at90° intervals, however, in other variations, receiving holes may bespaced apart at other angles depending upon the desireddegree-of-freedom and application. Also seen is an exploded assembly ofspool 206 removed from motor 204 exposing drive shaft 205. With motor204 displaced from backbone 202, the groove 230 is revealed as formed inthe backbone 202. This groove 230 may be depressed in backbone 202 topreferably match the radius of the motor 204 housing not only to helplocate the motor 204 adjacent to backbone 202, but also to help inreducing the overall diameter of the assembled segment. The motor 204may be attached to the backbone 202 by various methods, e.g., adhesives,clamps, bands, mechanical fasteners, etc. A notched portion 232 may alsobe formed in the cable guide 210 as shown to help in further reducingsegment diameter.

[0052] Prior to insertion into a patient, the endoscope 200 may be woundonto the rotating drum 184 within the rotary housing 180 of FIG. 5 forstorage and during use, where it may optionally be configured to have adiagnostic check performed automatically. When the endoscope 200 iswound onto the drum 184, adjacent segments 192 will have a predeterminedangle relative to one another, as determined initially by the diameterof the drum 184 and the initial configuration of the storage unit inwhich the endoscope 200 may be positioned. During a diagnostic checkbefore insertion, a computer may be configured to automatically sense ormeasure the angles between each adjacent segments 192. If any of theadjacent segments 192 indicate a relative measured angle out of apredetermined acceptable range of angles, this may indicate a segment192 being out of position and may indicate a potential point of problemsduring endoscope 200 use. Accordingly, the computer may subsequentlysound an audible or visual alarm and may also place each of the segments192 into a neutral position to automatically prevent further use or toprevent any trauma to the patient.

[0053] FIGS. 12-17 show the endoscope 100 of the present invention beingemployed for a colonoscopic examination of a patient's colon. In FIG.12, the endoscope body 102 has been lubricated and inserted into thepatient's colon C through the anus A. The distal end 108 of theendoscope body 102 is advanced through the rectum R until the first turnin the colon C is reached, as observed through the ocular 124 or on avideo monitor. To negotiate the turn, the selectively steerable distalportion 104 of the endoscope body 102 is manually steered toward thesigmoid colon S by the user through the steering control 122. Thecontrol signals from the steering control 122 to the selectivelysteerable distal portion 104 are monitored by the electronic motioncontroller 140. When the correct curve of the selectively steerabledistal portion 104 for advancing the distal end 108 of the endoscopebody 102 into the sigmoid colon S has been selected, the curve is loggedinto the memory of the electronic motion controller 140 as a reference.This step can be performed in a manual mode, in which the user gives acommand to the electronic motion controller 140 to record the selectedcurve, using keyboard commands or voice commands. Alternatively, thisstep can be performed in an automatic mode, in which the user signals tothe electronic motion controller 140 that the desired curve has beenselected by advancing the endoscope body 102 distally. In this way, athree dimensional map of the colon or path may be generated andmaintained for future applications.

[0054] Whether operated in manual mode or automatic mode, once thedesired curve has been selected with the selectively steerable distalportion 104, the endoscope body 102 is advanced distally and theselected curve is propagated proximally along the automaticallycontrolled proximal portion 106 of the endoscope body 102 by theelectronic motion controller 140, as described above. The curve remainsfixed in space while the endoscope body 102 is advanced distally throughthe sigmoid colon S. In a particularly tortuous colon, the selectivelysteerable distal portion 104 may have to be steered through multiplecurves to traverse the sigmoid colon S.

[0055] As illustrated in FIG. 13, the user may stop the endoscope 100 atany point for examination or treatment of the mucosal surface or anyother features within the colon C. The selectively steerable distalportion 104 may be steered in any direction to examine the inside of thecolon C. When the user has completed the examination of the sigmoidcolon S, the selectively steerable distal portion 104 is steered in asuperior direction toward the descending colon D. Once the desired curvehas been selected with the selectively steerable distal portion 104, theendoscope body 102 is advanced distally into the descending colon D, andthe second curve as well as the first curve are propagated proximallyalong the automatically controlled proximal portion 106 of the endoscopebody 102, as shown in FIG. 14.

[0056] If, at any time, the user decides that the path taken by theendoscope body 102 needs to be revised or corrected, the endoscope 100may be withdrawn proximally and the electronic motion controller 140commanded to erase the previously selected curve. This can be donemanually using keyboard commands or voice commands or automatically byprogramming the electronic motion controller 140 to go into a revisemode when the endoscope body 102 is withdrawn a certain distance. Therevised or corrected curve is selected using the selectively steerabledistal portion 104, and the endoscope body 102 is advanced as describedbefore.

[0057] The endoscope body 102 is advanced through the descending colon Duntil it reaches the left (splenic) flexure F, of the colon. Here, inmany cases, the endoscope body 102 must negotiate an almost 180 degreehairpin turn. As before, the desired curve is selected using theselectively steerable distal portion 104, and the endoscope body 102 isadvanced distally through the transverse colon T, as shown in FIG. 15.Each of the previously selected curves is propagated proximally alongthe automatically controlled proximal portion 106 of the endoscope body102. The same procedure is followed at the right (hepatic) flexure Fr ofthe colon and the distal end 108 of the endoscope body 102 is advancedthrough the ascending colon G to the cecum E, as shown in FIG. 16. Thececum E, the ileocecal valve V and the terminal portion of the ileum Ican be examined from this point using, the selectively steerable distalportion 104 of the endoscope body 102.

[0058]FIG. 17 shows the endoscope 100 being withdrawn through the colonC. As the endoscope 100 is withdrawn, the endoscope body 102 follows thepreviously selected curves by propagating the curves distally along theautomatically controlled proximal portion 106, as described above. Atany point, the user may stop the endoscope 100 for examination ortreatment of the mucosal surface or any other features within the colonC using the selectively steerable distal portion 104 of the endoscopebody 102. At any given time, the endoscope 100 may be withdrawn orback-driven by a desired distance.

[0059] In one preferred method according to the present invention, theelectronic motion controller 140 includes an electronic memory in whichis created a three-dimensional mathematical model of the patient's colonor other anatomy through which the endoscope body 102 is maneuvered. Thethree-dimensional model can be annotated by the operator to record thelocation of anatomical landmarks, lesions, polyps, biopsy samples andother features of interest. The three-dimensional model of the patient'sanatomy can be used to facilitate reinsertion of the endoscope body 102in subsequent procedures. In addition, the annotations can be used toquickly find the location of the features of interest. For example, thethree-dimensional model can be annotated with the location where abiopsy sample was taken during an exploratory endoscopy. The site of thebiopsy sample can be reliably located again in follow-up procedures totrack the progress of a potential disease process and/or to perform atherapeutic procedure at the site.

[0060] In one particularly preferred variation of this method, theelectronic motion controller 140 can be programmed, based on thethree-dimensional model in the electronic memory, so that the endoscopebody 102 will automatically assume the proper shape to follow thedesired path as it is advanced through the patient's anatomy. Inembodiments of the steerable endoscope 100 that are configured forautomatically advancing and withdrawing the endoscope body 102, asdescribed above in connection with FIGS. 3, 4 and 5, the endoscope body102 can be commanded to advance automatically though the patient'sanatomy to the site of a previously noted lesion or other point ofinterest based on the three-dimensional model in the electronic memory.

[0061] Imaging software would allow the three-dimensional model of thepatient's anatomy obtained using the steerable endoscope 100 to beviewed on a computer monitor or the like. This would facilitatecomparisons between the three-dimensional model and images obtained withother imaging modalities, for example fluoroscopy, radiography,ultrasonography, magnetic resonance imaging (MRI), computed tomography(CT scan), electron beam tomography or virtual colonoscopy. Conversely,images from these other imaging modalities can be used to map out anapproximate path or trajectory to facilitate insertion of the endoscopebody 102. In addition, images from other imaging modalities can be usedto facilitate locating suspected lesions with the steerable endoscope100. For example, images obtained using a barium-contrast radiograph ofthe colon can be used to map out an approximate path to facilitateinsertion of the endoscope body 102 into the patient's colon. Thelocation and depth of any suspected lesions seen on the radiograph canbe noted so that the endoscope body 102 can be quickly and reliablyguided to the vicinity of the lesion.

[0062] Imaging modalities that provide three-dimensional information,such as biplanar fluoroscopy, CT or MRI, can be used to program theelectronic motion controller 140 so that the endoscope body 102 willautomatically assume the proper shape to follow the desired path as itis advanced through the patient's anatomy. In embodiments of thesteerable endoscope 100 that are configured for automatically advancingand withdrawing the endoscope body 102, the endoscope body 102 can becommanded to advance automatically though the patient's anatomy alongthe desired path as determined by the three-dimensional imaginginformation. Similarly, the endoscope body 102 can be commanded toadvance automatically to the site of a suspected lesion or other pointof interest noted on the images.

[0063] As described above, the axial motion transducer 150 can be madein many possible configurations, e.g., shown in FIG. 2 as a ring 152. Itfunctions partially as a fixed point of reference or datum to produce asignal indicative of the axial position of the endoscope body 102 withrespect to the fixed point of reference. The axial motion transducer 150may use optical, electronic or mechanical methods to measure the axialposition of the endoscope body 102. One preferable embodiment of thedatum 234 is shown schematically in FIGS. 18-20 as an instrumentedspeculum which may be placed partially into the rectum of the patient orat least adjacent to the anus A of a patient. Prior to the segmentedendoscopic body 238 being inserted into the anus A, it is preferablyfirst passed through the datum channel 236 of datum 234. The datum 234may house the electronics and mechanical assemblies necessary to measurethe depth of insertion, as discussed below, and it may also provide afixed, solid base to aid in co-locating the endoscopic body 238 adjacentto the anus A or body orifice as well as provide a base to stabilize andinsert the endoscope body 238 into the orifice. The instrumentedspeculum may be constructed of a biocompatible material, such asinjection-molded plastic, and house inexpensive electronics, as thespeculum may preferably be disposable.

[0064] As the endoscopic body 238 passes through the datum channel 236,one preferable optical method of measuring the depth of insertion andaxial position may involve measurement through the use of reflectiveinfra-red sensors mounted on the datum 234. The outer surface of theendoscopic body 238 may have hatch marks or some other indicative orreflective marking placed at known intervals along the body 238. As theendoscopic body 238 is advanced or withdrawn through the anus A and thedatum channel 236, an optical sensor can read or sense the hatch marksand increment or decrement the distance traveled by the endoscopic bodyaccordingly. Thus, a sensor reading such marks may have an output thatregisters as a logic-level “1” or “ON” when a mark is sensed and alogic-level “0” or “OFF” when no mark is sensed. By counting or trackingthe number of 1-to-0 transitions on a sensor output, the depth may bemeasured accordingly. Thus resolution of the depth measurement may bedetermined in part in this embodiment by the spacing between the hatchmarks.

[0065] A simplified representation of how the distance may be used toadvance the device may be seen in FIG. 18. The endoscopic body 238 isadvanced until the distal tip reaches a depth of L₁, as measured fromthe midpoint of the datum speculum 234. At this depth, it is necessaryfor the user to selectively steer the tip to follow the sigmoid colon Ssuch that the body forms a radius of curvature R₁. Once the position anddepth of this feature has been defined by the distal tip, any proximalsegment that reaches this depth of L₁ can be commanded to configureitself in the same manner as the distal tip segment until it hasachieved the correct combination of bends to negotiate the turn. As thebody 238 is further advanced, as seen in FIG. 19, it will eventuallyreach the second major bend at a depth of L₁+L₂. Accordingly, as for L₁,any segment that is advanced and reaches a depth of L₁+L₂ will likewisebe commanded to execute a turn as defined by the distal tip beingselectively steered when it first passed the second bend into thedescending colon D. Again as the body 238 is further advanced, as shownin FIG. 20, any subsequent segment that is advanced to reach a depth ofL₁+L₂+L₃ will be commanded to execute and negotiate the turn to followthe transverse colon T, again where the original curve has been definedby the selectively steerable distal tip.

[0066]FIG. 21 shows a schematic of one embodiment of a control systemwhich may be used to control and command the individual segments of asegmented endoscopic device of the type shown in FIGS. 8-11B. As seen, amaster controller 248, which preferably resides at a location away fromthe segmented endoscope 242, may be used to control and oversee thedepth measurement as the endoscope 242 is inserted 256 into a patient.The master controller 248 may also be used to manage and communicate theactuation efforts of each of the joints and segments 242 ₁ to 242 _(n)by remaining in electrical communication through communications channels252, which may include electrical wires, optical fibers, wirelesstransmission, etc. As also shown in this embodiment, the mastercontroller 248 may also be in communication with datum 244 via datumcommunication channel 254 to measure and track the depth of insertion ofthe endoscope 242 as it passes through datum channel 246, as describedabove.

[0067] The segmented embodiment 242 may be comprised of a number ofindividual segments 242 ₁ to 242 _(n) (only segments 242 ₁ to 242 ₅ areshown for clarity). Each segment 242 ₁ to 242 _(n) preferably has itsown separate controller 250 ₁ to 250 _(n), respectively, containedwithin each segment. Types of controllers used may includemicrocontrollers. The controllers 250 ₁ to 250 _(n) may serve to performseveral functions, e.g., measuring the angle of each segment joint ineach of the two axes α and β, as described above, activating the motorscontained within the segments 242 ₁ to 242 _(n) to actuate endoscope 242movement, and receiving and handling commands issued from the mastercontroller 248. Having individual controllers 250 ₁ to 250 _(n) in eachrespective segment 242 ₁ to 242 _(n) enables each segment to manage therequirements for a given configuration locally at the controller levelwithout oversight from the master controller 248 after a command hasbeen issued.

[0068] Accordingly, a flow chart embodiment for the master controlleralgorithm 260, as shown in FIG. 22, may be used to control the overallfunction during insertion into a patient. During an initial step 262,the overall system (such as that shown in FIG. 21) may be initializedwhere all position sensors are zeroed. The master controller 248 thenenters a waiting state where it continually monitors the depthmeasurement gathered by the datum 244 located proximally of bodyopening, as shown in step 264. Once movement, i.e., depth measurement,is detected by the datum 244 in step 264, the master controller 248 thendetermines whether the direction of motion of the endoscopic body 242 isbeing advanced, i.e., inserted, or withdrawn. As shown in step 266, ifthe endoscopic body 242 is being inserted and the depth is increasing,the current depth is incremented, as in step 268; otherwise, the currentdepth is decremented, as in step 270. Once the depth has beendetermined, the master controller 248 communicates to each segment 242 ₁to 242 _(n) individually and commands each to actuate to adjust orcorrect its position relative to the adjacent segments for the currentdepth, as shown in step 272. Afterwards, the master controller 248continues to monitor any changes in depth and the process is repeated asshown.

[0069] To maintain the orientation of each axis α and β and thepositioning and the depth of each segment 242 ₁ to 242 _(n), a dataarray, or similar data structure, may be used by the master controller248 to organize the information, as shown in the following Table 1.Depth index D₁ to D_(n) is used here to denote the individual hatchmarks, as seen in FIG. 21, and the distance between the hatch marks is aknown value. Thus, the resolution with which the endoscope 242 canmaintain its shape may depend at least in part upon the spacing betweenthe depth indices D₁ to D_(n). Moreover, the number and spacing of theindices D₁ to D_(n) may be determined and set according to the specificapplication and necessary requirements. Additional smoothing algorithmsmay be used and implemented to further create gradual transitionsbetween segments 242 ₁ to 242 _(n) or between discrete depth measurementindices D₁ to D_(n). TABLE 1 Data array of individual segments. DepthSegment 1 Segment 2 Segment N Index α/β α/β . . . α/β D₁ α_(D1)/β_(D1)α_(D1)/β_(D1) . . . α_(D1)/β_(D1) D₂ α_(D2)/β_(D2) α_(D2)/β_(D2) . . .α_(D2)/β_(D2) D₃ α_(D3)/β_(D3) α_(D3)/β_(D3) . . . α_(D3)/β_(D3) . . . .. . . . . . . . . . . D_(n) α_(Dn)/β_(Dn) α_(Dn)/β_(Dn) . . .α_(Dn)/β_(Dn)

[0070]FIG. 23 shows a flowchart embodiment of the segment controlleralgorithm 280. While the master controller 248 manages the measurementof the overall depth of insertion of the endoscope 242 and determinesthe overall shape, it may also communicate with the individualcontrollers 250 ₁ to 250 _(n) in each segment 242 ₁ to 242 _(n)respectively, so that the computation task of managing the motion of theentire system is preferably distributed.

[0071] As discussed above, the individual controllers 250 ₁ to 250 _(n)may serve a variety of functions, including accepting commands from themaster controller 248, managing communications with other controllers asnecessary, measuring and controlling the position of individual segments242 ₁ to 242 _(n), and performing diagnostics, error checking, etc.,among other things. The algorithm to control each segment 242 ₁ to 242_(n) is preferably similar for each segment; although the lead segment242 ₁ or first few segments are under the guidance of the physician toselectively control and steer so that the desired curve is set for anappropriate path to be followed.

[0072] The initial step 282 for the system preferably first occurs whereall communications, actuator (or motor), position sensors, andorientation are initialized. The controllers 250 ₁ to 250 _(n) may thenwait to receive any communications from the master controller 248 instep 284. If no communications are received, the controllers 250 ₁ to250 _(n) preferably enter into a main loop while awaiting commands. Whena command is received, each of the controllers 250 ₁ to 250 _(n) mayrequest diagnostic data, as in step 286. If diagnostic data isrequested, the appropriate diagnostics are performed in step 288 and theresults are sent back to the master controller 248, as in step 290. Ifno diagnostic data is requested in step 286, each of the controllers 250₁ to 250 _(n) in step 292 may then determine whether actuation or motionhas been requested by the master controller 248. If no actuation ormotion has been requested, the relevant segment may continue to receivea command; otherwise, the relevant segment determines whether a commandhas been issued affecting the segment axis α, as in step 294, or segmentaxis β, as in step 300. If the segment axis α is to be altered, thecommand is sent to the α axis PID controller (or to a superior controlscheme) in step 296, and the appropriate actuator is subsequentlyactivated effecting the actuation of the segment in the α axis, as instep 298. Likewise, if the segment axis β is to be altered, either aloneor in conjunction with the α axis, the command is sent to the β axis PIDcontroller (or to a superior control scheme) in step 302, and theappropriate actuator is subsequently activated effecting the actuationof the segment in the β axis, as shown in step 304. Once the appropriatecommands have been effectuated, the controllers 250 ₁ to 250 _(n) againenter the main loop to await any further commands.

[0073] Although the endoscope of the present invention has beendescribed for use as a colonoscope, the endoscope can be configured fora number of other medical and industrial applications. In addition, thepresent invention can also be configured as a catheter, cannula,surgical instrument or introducer sheath that uses the principles of theinvention for navigating through tortuous body channels.

[0074] In a variation of the method that is particularly applicable tolaparoscopy or thoracoscopy procedures, the steerable endoscope 100 canbe selectively maneuvered along a desired path around and between organsin a patient's body cavity. The distal end 108 of the endoscope 100 isinserted into the patient's body cavity through a natural opening,through a surgical incision or through a surgical cannula, introducer,or trocar. The selectively steerable distal portion 104 can be used toexplore and examine the patient's body cavity and to select a patharound and between the patient's organs. The electronic motioncontroller 140 can be used to control the automatically controlledproximal portion 106 of the endoscope body 102 to follow the selectedpath and, if necessary, to return to a desired location using thethree-dimensional model in the electronic memory of the electronicmotion controller 140.

[0075] A further variation which involves a non-contact method ofmeasurement and tracking of the steerable endoscope is seen in FIGS. 24to 26. This variation may be used in conjunction with sensor-basedsystems or transponders, e.g., coils or magnetic sensors, for trackingof the endoscope via magnetic detection technology or a navigationalsystem or device external to the patient employing a scheme similar tothat used in global positioning systems (GPS). Magnetic sensors may beused, but coils are preferable because of their ability to resonate atdistinct frequencies as well as their ability to have a unique“signature”, which may allow for the use of several different coils tobe used simultaneously. Seen in FIG. 24, the endoscopic body 238 may beinserted into a patient via the anus A. Located on the endoscope body238 are transponders 310 to 318 which may be placed at predeterminedpositions such as the selectively steerable distal tip.

[0076] As the endoscope 238 is advanced through the descending D andtransverse colon T, the transponders may be detected by an externalnavigational unit 320 which may have a display 322 showing the positionof the endoscope 238 within the patient. As the endoscope 238 is furtheradvanced within the patient, as seen in FIG. 26, the navigational unit320 may accordingly show the corresponding movement. The use of anavigational unit 320 presents a non-contact method of navigating adevice such as the endoscope 238 and may be used to measure and locatedifferent positions within the patient relative to anatomical landmarks,such as the anus A or ileocecal valve. Furthermore, such an embodimentmay be used either alone or in conjunction with the datum speculum 234instrumentation as described above.

[0077] Use of the navigational unit 320 may also be particularlyapplicable to laparoscopy or thoracoscopy procedures, as describedabove, in spaces within the body other than the colon. For example, theendoscope 238 may also be selectively maneuvered along a desired patharound and between organs in a patient's body cavity through any of theopenings into the body discussed above. While being maneuvered throughthe body cavity, the endoscope 238 may be guided and tracked by theexternally located navigational unit 320 while the endoscope's 238location may be electronically marked and noted relative to apredetermined reference point, such as the datum, or relative toanatomical landmarks, as described above.

[0078] While the present invention has been described herein withrespect to the exemplary embodiments and the best mode for practicingthe invention, it will be apparent to one of ordinary skill in the artthat many modifications, improvements and subcombinations of the variousembodiments, adaptations and variations can be made to the inventionwithout departing from the spirit and scope thereof.

We claim:
 1. An apparatus for insertion into a body cavity, comprising:an elongate body having a proximal end and a selectively steerabledistal end and defining at least one lumen therebetween, the elongatebody comprising a plurality of segments interconnected via joints; andat least one motor attached to each of at least a majority of segmentsfor actuating an adjacent segment and wherein each motor isindependently controllable, wherein when the distal end assumes aselected curve, the plurality of segments are configured to propagatethe selected curve along the elongate body by each motor selectivelyactuating the adjacent segment.